In the prior art, typically sails have been constructed by sewing a woven material. Woven material is based on the weft and warp technology with the yarns running over and under, thus introducing inherent weakness in the sail when it is loaded on the bias or when the sail is subjected to a load such that the load line does not follow the threads, e.g., the warp threads, or expressing it otherwise, when the warp threads do not follow the load lines in a sail and "run off" the cloth.
In accordance with a number of techniques, panels in the sail are rotated so that appropriate panels can be cut and made to follow the line representing the force being exerted on the sail. Typically the current sails are made in panels that form catenaries connecting a clew and a head, a head and a tack, and a tack and a clew. In order to reduce the cost as well as the weight of the sail, the best prior art warp and weft based sails describing this problem of orientation of catenaries is found in my U.S. Pat. No. 4,593,639, which is incorporated by reference herein
Further, and as a sizable improvement thereover, my U.S. Pat. No. 4,708,080 has advanced the art by a great step, eliminating altogether the warp, weft and cloth-panel orientation technology. The sails made in accordance with my U.S. Pat. No. 4,708,080 represent and entirely rely on the proper shaping of the sail by the use of threads in a properly tailored manner for each panel using a simple panel layout of a reduced number of panels. Thus, proper orientation of each of the threads in a panel is achieved. Proper thread size and thread count density in a particular location in a particular panel is now possible. Each panel bears the stress on it in a manner causing substantially reduced distortion of the sail when the sail is subjected to use for its intended purpose. Accordingly, the predeterminately disposed threads in a sail panel now form the proper catenary in a sail in an improved manner, further reducing the weight of the sail and improving its performance and durability. U.S. Pat. No. 4,708,080 is also incorporated by reference herein.
In these two patents, as well as in related U.S. Pat. Nos. 4,624,205, 4,702,190, 4,815,409 and 4,831,953 are included a number of references. These references illustrate the prior art and the background for the inventions. These references mentioned in the above patents are considered as part of the background summed up herein.
A special mention, however, should be made to U.S. Pat. No. 3,954,076 to Fracker, mentioned in U.S. Pat. No. 4,593,639, which discloses the reinforcement in the tack, clew and head of a said by having fanned rectangles of the sail material sewn onto the sail, thus distributing the load from the clew, tack or head.
Subsequent developments made after the filing of U.S. Pat. No. 4,593,639 have shown that the structural members have far better reinforcement capabilities, especially when used in the manner such as disclosed in U.S. Pat. No. 4,593,639, thus representing the technology of joining, e.g., the tack and the clew of a sail in a structure. By such structure incorporation in sails, superior sails have been achieved.
Although the improvements shown in U.S. Pat. No. 4,593,639 have greatly benefited the sailmaking art and a number of sails have been made by this technology, further improvements shown by U.S. Pat. No. 4,708,080 and the associated cost savings have provided a greater incentive to develop further improvements.
Thus, the present invention relates to further improvements associated with the technology represented by U.S. Pat. No. 4,708,080.